Servo information is stored to media in a deliberate manner as part of the process of preparing the media for use in a data storage device. The servo information delineates the storage area in a data storage disc, for example, into addressable locations at the intersection of a designated radial position, such as track number, and a designated rotational position, such as sector number. Pluralities of discrete servo sectors form rings across the storage space, be they concentric or spiral rings. A data transfer element continuously feeds the servo information back to a servo control system as the element is moved about in the storage area. The control system utilizes the servo information to position the element, such as in deriving an optimal trajectory for moving the element to a desired track and maintaining the element at the desired track.
There are various ways to store servo information to the media. Generally, they can be broadly categorized as either an in-situ servowriting approach or an ex-situ servowriting approach, or a combination of the two approaches. In a disc drive, for example, in-situ approaches include storing servo data to the disc after it has been installed as a component part of the disc drive. The actuator in the disc drive is used to store the servo data to each disc. In some cases an external positioner engages the actuator and positionally controls it. In other cases seed data is first stored to the disc and the disc drive then executes programming instructions that propagate the servo data from the seed data (self-servo schemes).
Ex-situ approaches store some or all of the servo data to a disc before it is installed in the disc drive. Servowriters of this type typically employ an actuator supporting an element in a data storage relationship with the disc which is mounted on a rotating spindle, similar to the disc drive.
In addition to servowriting, media certification is also performed to ensure a requisite quality exists in the media's capability to store data and retain it. Generally, certification involves writing a preselected user data pattern in the storage area and then analyzing a read signal for indications of flaws in the media. A flaw may exist because of nonconformities in the media, or may be due to a presence of contamination or debris. Screening the media for flaws before it escapes the factory or even reaches the finished goods is essential to building the expected quality and reliability into the storage devices.
Both servowriting and certification entail carrying out relatively long processes within what is a highly automated and fast paced manufacturing system. The claimed embodiments are directed to improvements in both the effectiveness and the efficiency with which the servowriting and certifying processes are performed.